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J Am Acad Audiol 1999; 10(05): 273-284
DOI: 10.1055/s-0042-1748498
Original Article

Field Trial Evaluations of a Switched Directional/Omnidirectional In-the-Ear Hearing Instrument

David A. Preves
Micro-Tech Hearing Instruments, Minneapolis, Minnesota
,
Carol A. Sammeth
Roudebush VA Medical Center, Indianapolis, Indiana, currently Otologics, LLC, Bolder, Colorado
Department of Otolaryngology, Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, Indiana
,
Michael K. Wynne
Department of Otolaryngology, Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, Indiana
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Abstract

The use of directional microphones is one of the few methods available for hearing aids to increase the signal-to-noise ratio. The smaller microphones available with today's technology have increased the viability of their application for in-the-ear (ITE) hearing aids. This study evaluated an ITE hearing aid containing two nondirectional microphones that provides wearer-selectable omnidirectional/directional operating modes. Ten sensorineural hearing-impaired patients were fitted binaurally. During the first trial period, the low-frequency gain decrease produced by the directional mode was not compensated for. The frequency responses were matched during the second trial period. For both trial periods, Hearing in Noise Test results using two uncorrelated noise sources indicated significant speech recognition improvements for the directional mode relative to the omnidirectional mode. Responses on Abbreviated Profile of Hearing Aid Benefit questionnaires, paired-comparison judgments, and interview data revealed that most subjects preferred the directional mode in noisier environments, but many also preferred the omnidirectional mode in quiet listening.

Abbreviations: AGC-O = automatic gain control with output compression, APHAB = Abbreviated Profile of Hearing Aid Benefit, BTE = behind-the-ear hearing aid, CD = compact disc, Dl = Directivity Index, HINT = Hearing in Noise Test, ITE = in-the-ear hearing aid, MCL = most comfortable listening level, NAL-R = National Acoustics Laboratories' revised prescriptive formula, SNR = signal-to-noise ratio, UCL = uncomfortable loudness level

Key Words

Amplification - directional microphones - hearing aids - speech recognition


Publication History

Article published online:
29 April 2022

© 1999. American Academy of Audiology. This article is published by Thieme.

Thieme Medical Publishers, Inc.
333 Seventh Avenue, 18th Floor, New York, NY 10001, USA

 

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